Method and device for verifying the integrity of gas valve operators in a gas appliance

Abstract

A method and device for verifying the integrity of each operator of a gas valve including two operators disposed in succession on a passage path for the gas directed to a burner; the operator being subjected to command action by a corresponding actuator controlled by a command and control unit adapted to sense the presence of the flame in the burner, which is correlated with the gas flow rate reaching this burner. Each operator is made to close alternately, with corresponding cessation of gas feed to the burner and successive sensing of the extinguishing of the flame at the burner within a predefined time period, power to these operators being completely interrupted if it is sensed after said time period that the flame is extinguished.

The invention claimed is: 
     
       1. A method for verifying the integrity of each operator of a gas valve of a gas appliance, the gas valve comprising two said operators disposed in succession along a gas passage path through the gas valve configured for supplying gas to a burner in the gas appliance, the method comprising:
 having each of said operators comprise:
 a body accommodating a portion of the gas passage path, 
 a movable valving member disposed within the body to close or open the respective portion of the gas passage path, and 
 an electrically powered valving member actuator for operating the movable valving member to regulate closing or opening the respective portion of the gas passage path according to burner extinguishing requests, 
 
 subjecting each of the valving member actuators to command action by a corresponding operator actuator, 
 controlling each of the operator actuators in its turn by a command and control unit which supervises the gas appliance operation, wherein each operator actuator is electrically controlled, and controlling the electrical feed current to the operator actuator causes a minimum closure action of the respective gas passage path, the minimum closure action being defined by an electrical feed current different from zero but sufficient to cause closure of the respective gas passage path by the intervention of the respective operator, 
 determining the electrical feed current sufficient to close the respective valve passage path portion by reducing the electrical feed current, starting from the electrical feed current which is able to maintain the operator in a position in which the operator does not choke the gas passage path, 
 wherein the determination is performed at predetermined time intervals to evaluate if there has been decay in the electrical feed current sufficient to close the respective valve passage path portion, 
 the command and control unit sensing a flame signal corresponding to the presence of the flame in the burner of the gas appliance proportional to the gas flow rate reaching the burner, 
 each operator being made to close alternately, with corresponding cessation of gas feed to the burner and successive sensing of the extinguishing of the flame at the burner, 
 detecting incorrect functionality of at least one of the operators whenever it is sensed that the flame is extinguished only at a time after a predefined limit has been exceeded, this indicating the incorrect functionality of the operator subjected to closure; and 
 upon detecting the incorrect functionality of at least one of the operators, performing the additional step of permitting each of the operators to simultaneously close the gas passage to bring the gas passage into a safety position. 
 
     
     
       2. The method as claimed in  claim 1 , wherein the predefined limit is a time period between 0 and 30 seconds, wherein each operator actuator is a stepping motor or solenoid motor. 
     
     
       3. The method as claimed in  claim 1 , wherein electrical feed current sufficient to close the respective valve passage path portion is achieved by gradually reducing the electrical feed current, starting from the electrical feed current which is able to maintain the operator in a position in which the operator does not choke the gas passage path. 
     
     
       4. The method as claimed in  claim 1 , wherein each valving member actuator is an electric motor, a minimum closure action of the respective gas passage path portion being defined by a movement of the motor which enables the closure of the respective gas passage path of the gas valve to close within a predetermined time interval. 
     
     
       5. The method as claimed in  claim 1 , implemented at each burner extinguishing request. 
     
     
       6. The method as claimed in  claim 1 , implemented at predefined time intervals. 
     
     
       7. The method as claimed in  claim 1 , implemented after a predefined number of ignitions. 
     
     
       8. The method as claimed in  claim 1 , implemented by forcing the extinguishing of the burner if the burner is continuously in operation. 
     
     
       9. The method as claimed in  claim 2 , wherein the predefined time period is between 0 and 10 seconds. 
     
     
       10. The method as claimed in  claim 9 , wherein the predefined time period is between 0 and 3 seconds. 
     
     
       11. The method as claimed in  claim 1 , wherein the additional step comprises the step of performing a safety closure of each operator by permitting the corresponding operator actuator for each operator to completely close the respective gas passage path portion, wherein a safety closure of the gas passage path occurs. 
     
     
       12. The method of  claim 1 , wherein the gas appliance is a boiler. 
     
     
       13. The method of  claim 1 , wherein the gas appliance is a water heater. 
     
     
       14. The method as claimed in  claim 1 , wherein each valving member actuator is an electric solenoid, a minimum closure action of the respective gas passage path portion being defined by an electric current value to the solenoid which enables the closure of the respective gas passage path portion of the gas valve within a predetermined time interval. 
     
     
       15. The method as claimed in  claim 1 , wherein each valving member actuator is an electric motor, a minimum closure action of the respective gas passage path portion being defined by an electric current value to the electric motor which enables the closure of the respective gas passage path portion of the gas valve within a predetermined time interval. 
     
     
       16. The method according to  claim 1 , wherein each valving member actuator is a solenoid. 
     
     
       17. The method according to  claim 16 , wherein each operator actuator is a stepping motor or solenoid motor. 
     
     
       18. A method for verifying the integrity of each operator of a gas valve of a gas appliance, the gas valve comprising two said operators disposed in succession along a gas passage path through the gas valve configured for supplying gas to a burner in the gas appliance, the method comprising:
 having each operator comprise:
 a body accommodating a portion of the gas passage path, 
 a movable valving member disposed within the body, and 
 an electrically powered valving member actuator operating the movable valving member to regulate closing or opening the respective portion of the gas passage path according to burner extinguishing requests, 
 
 subjecting each of the valving member actuators to command action by a corresponding operator actuator, 
 adapting each of the operators to regulate closing or opening of the gas passage path according to burner extinguishing requests; 
 controlling electrical feed current from each of the operator actuators to each of the valving member actuators causing a minimum closure action of the gas passage path, the minimum closure action being defined by an electrical feed current different from zero but sufficient to cause closure of the gas passage by the intervention of the operator; 
 determining the electrical feed current sufficient to close the respective valve passage path portion by reducing the electrical feed current, starting from the electrical feed current which is able to maintain the operator in a position in which the operator does not choke the gas passage path, 
 wherein the determination is performed at predetermined time intervals to evaluate if there has been decay in the electrical feed current sufficient to close the respective valve passage path portion, 
 controlling each of the operator actuators in its turn by a command and control unit which supervises the gas appliance operation; 
 sensing a flame signal corresponding to the presence of the flame in a burner of the gas appliance proportional to the gas flow rate reaching the burner by the command and control unit; 
 alternating closing each operator with corresponding cessation of gas feed to the burner and successive sensing of the extinguishing of the flame at the burner; 
 interrupting the gas feed being detected due to incorrect functionality of at least one of the operators whenever it is sensed that the flame is extinguished only at a time after a predefined limit has been exceeded, this indicating the functionality of the operator subjected to closure is not completely correct; and 
 performing the additional step of permitting each of the operators to simultaneously close the gas passage to bring the gas passage into a safety position upon detecting incorrect functionality of at least one of the operators. 
 
     
     
       19. The method according to  claim 18 , wherein each valving member actuator is a solenoid. 
     
     
       20. The method according to  claim 19 , wherein each operator actuator is a stepping motor or solenoid motor.